The present invention relates generally to the field of solidification and solidification matrices for detergent compositions. There are numerous solid detergent compositions commercially available that incorporate solidification technology to form solid block detergents. See e.g., U.S. Pat. Nos. RE32,762, RE32,818, 4,595,520 and 4,680,134. Despite the use of solidification technologies, most solid detergents contain hydratable salts and water causing a lack of dimensional stability due to the kinetic and/or thermodynamic instability of the hydratable salts used in the solid compositions.
Soda ash or sodium carbonate is a commonly used hydratable salt that can lead to unstable detergent compositions in the presence of water. Changes in water content or temperature can cause structural and dimensional instability and significantly impact the rate in which the solid composition solidifies. For example, the solid composition may crack, crumble, swell, or become incompatible with dispensing equipment and packaging. The rate of solidification may also be significant in order to optimize the processing of the solid composition. Binding agents may function by controlling the movement of water within a solid composition and/or forming favorable interactions with other components of the composition resulting in a dimensionally stable solid.
Phosphorous-containing binding agents and hardness sequestrants were commonly used for solidification matrices for detergent compositions. However, due to environmental concerns, it is not desirable to use phosphorous-containing compounds. Many products replaced phosphorous-containing binding agents with nitrilotriacetic acid (NTA)-containing components. However, concerns over the carcinogenic effects of NTA-containing components, such as aminocarboxylates, in detergent compositions make these compounds undesirable as well. Therefore, there is an ongoing need to provide alternative phosphorous-free and/or NTA-free solidification technologies for use with solid detergents. However, the lack of predictability in the solidification process and the lack of predictability of dimensional stability in solid compositions have hampered efforts to successfully replace phosphorous and/or NTA-containing components with environmentally-friendly substitutes.
Accordingly, it is an objective of the invention to identify biodegradable binding agents for use in solid detergent compositions.
A further object of the invention is to identify binding agents capable of providing exceptional dimensional stability for a solid detergent composition.
Still further, an object of the invention is to develop such dimensionally stable, solid detergent composition that may be, free of phosphorus and NTA.